class Shape:
    def area(self):
        return 0
class Circle(Shape):
    def __init__(self,r):
        self.r = r
    def area(self):
        return (3.14*self.r*self.r)
class Square(Shape):
    def __init__(self,side):
        self.side = side
    def area(self):
        return (self.side*self.side)